Carbon nanotube network-based nano-composites

ABSTRACT

Techniques for manufacturing carbon nanotube network-based nano-composites are provided. In some embodiments, a nano-composite manufacturing method includes forming a carbon nanotube (CNT) network, immersing the CNT network into an electroplating solution, applying electrical energy, and relaying the electrical energy flow to produce a nano-composite having uniform conductive bridges on the CNT network.

TECHNICAL FIELD

The present disclosure relates generally to nano-composites and, moreparticularly, to carbon nanotube (CNT) network-based nano-composites.

BACKGROUND

Recently, CNTs have attracted great attention in many research areas dueto their superior mechanical, thermal and electrical properties thatmake them potentially useful in various applications in nanotechnology,electronics, optics and other fields.

CNTs are generally synthesized by chemical vapor deposition (CVD), laserablation or arc discharge, and are categorized as single-wallednanotubes (SWNTs) and multi-walled nanotubes (MWNTs). MWNTs includeconcentric cylinders with the smallest cylinder in the middleimmediately surrounded by a larger cylinder which in turn is immediatelysurrounded by an even larger cylinder. Here, each cylinder represents a“wall” of CNTs, hence the name “multi-walled” nanotubes.

Although CNTs have been extensively utilized in many applications due totheir extraordinary physical properties, a major drawback of CNT-basedapplications is irreproducibility. It is difficult to reproduce singleCNT devices consistently due to the variations in chirality and geometryof CNTs. However, such individual variation is suppressed in the CNTnetwork by an ensemble averaging over a large number of CNTs. CNTnetworks are reproducible and fabricated at low cost with highefficiency by using the processes of dip-coating, spraying, vacuumfiltration, and so on. These characteristics make them ideal candidatesfor various applications. For example, CNT networks have been studiedfor thin-film transistors, diodes, strain and chemical sensors, fieldemission devices, and transparent conductive electrodes. Especially, CNTtransparent conducting electrodes (CNT-TCE) may provide a criticalcomponent of next generation flexible displays due to their excellentelectrical properties and mechanical flexibility.

TCE is used for various applications such as liquid crystal display(LCD), plasma display panel (PDP), and touchpads. Indium tin oxide (ITO)is a general TCE material suitable for most applications, but indium isa rare material currently produced only in Russia. As demand for TCEcontinues to increase, the price of indium has rapidly increased. TCE isgenerally made by coating the ITO layer on a glass substrate or aflexible polymer substrate. A drawback is that, since ITO is a brittlematerial, it is not suitable for flexible display which has become ofgreat interest recently. Therefore, it is necessary to develop a lowprice TCE with enough flexibility.

Another drawback is that, even though individual CNTs have highelectrical conductivity, the resistances at the junctions between oneCNT to another are considered as a dominant bottleneck tocommercializing CNT-TCE with low resistivity. Still another drawback isthe complex and inefficient synthesis techniques which are presentlyrequired to utilize the outstanding physical properties of CNTs.

SUMMARY

Nano-composites, methods, and apparatus for manufacturing anano-composite are provided. In one embodiment, an electroplatingapparatus includes a power supply, a CNT network, an electroplatingsolution, an anode, and a relay.

In another embodiment, a method for manufacturing a nano-compositeincludes forming a CNT network, immersing the CNT network into anelectroplating solution, applying an electrical energy, and relaying theelectrical energy flow to produce a nano-composite having uniformconductive bridges on the CNT network.

In still another embodiment, the present disclosure provides a CNTnetwork-based nano-composite.

The Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an illustrative embodiment of an electroplating apparatusfor manufacturing a nano-composite.

FIG. 2 shows an illustrative embodiment of a Scanning ElectronMicroscopy (SEM) image of a portion of the nano-composite electroplatedwith metal using the apparatus of FIG. 1.

FIG. 3 an illustrative embodiment of a SEM image of another portion ofthe nano-composite electroplated with metal using the apparatus of FIG.1.

FIG. 4 shows another illustrative embodiment of an electroplatingapparatus for manufacturing a nano-composite.

FIG. 5 shows still another illustrative embodiment of an electroplatingapparatus for manufacturing a nano-composite.

FIG. 6 is a schematic diagram of an illustrative embodiment of a CNTnetwork with metal bridges.

FIG. 7 is a schematic diagram of an illustrative embodiment of a CNTnetwork with conductive polymer bridges.

FIG. 8 is a flow chart of an illustrative embodiment for manufacturing aCNT network-based nano-composite.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here. It will be readily understood that the components of thepresent disclosure, as generally described herein, and illustrated inthe Figures, may be arranged, substituted, combined, and designed in awide variety of different configurations, all of which are explicitlycontemplated and make part of this disclosure.

As used herein, a “junction” generally means a place where CNTs join orcross one another. The term “junction” also encompasses a situationwhere CNTs are adjacent to one another with narrow gaps so as to bebridged by a conductive substance, wherein the size and density of theconductive bridge is within the range to not seriously undermine thetransparency of the manufactured nano-composite for its various uses.The size and density of the conductive bridges are also within the rangeto reduce the resistance between the CNTs within the CNT network.

FIG. 1 shows an illustrative embodiment of an electroplating apparatus100 for manufacturing a nano-composite. As depicted, the electroplatingapparatus 100 includes a power supply 102, a container 104, an anode106, an electrode 108, a CNT network 110, a substrate 112, and anelectroplating solution 114. The power supply 102 is electricallycoupled to the anode 106 and the electrode 108.

The CNT network 110 attached to the electrode 108 is immersed into theelectroplating solution 114 to perform electroplating thereon.Electrical energy is applied across the anode 106 and the electrode 108immersed in the electroplating solution 114, causing the CNT network 110to be deposited with the electroplating substance, for example metal(indicated by the symbol “M”) in the electroplating solution 114 toproduce a nano-composite. Various types of metals or conductive polymersmay be used for forming the electroplating solution 114. In this way,electroplating substance may work as bridges between CNTs, therebyreducing resistance between crossover CNTs within the CNT network 110.

FIGS. 2 and 3 show illustrative embodiments of SEM images of differentportions of the nano-composite manufactured by using the apparatus 100of FIG. 1. As depicted in FIG. 2, the portion of the nano-composite,which is near the electrode 108 has a high density of electroplatingsubstance (e.g., Cu) on the CNT network 110. On the other hand, theother portion of the nano-composite, which is far from the electrode108, has a low density of electroplating substance, as illustrated inFIG. 3, although the density distribution of the CNTs on the CNT network110 is uniform. With respect to FIGS. 2 and 3, the CNT network 110 waselectroplated in the electroplating solution 114 over a long period oftime and thus a good deal of the electroplating substance was depositedon the CNT network 110, especially on the portion of the CNT network 110near the electrode 108, to make the CNTs of FIG. 2 more opaque thanthose of FIG. 3. Considering that the electroplating substance such asmetals or conductive polymers tends to gather around the electrode 108,for the nano-composite manufactured by using the apparatus 100 of FIG.1, the density distribution of the electroplating substance is notuniform over the CNT network 110, resulting in the non-uniformelectrical resistance and transparency according to the region of themanufactured nano-composite.

FIG. 4 shows another illustrative embodiment of an electroplatingapparatus 400 for manufacturing a nano-composite. As depicted, theelectroplating apparatus 400 includes a power supply 402, a container404, an anode 406, two electrodes 408, 410, a CNT network 412, asubstrate 414, an electroplating solution 416, and a relay 418. Thepower supply 402 is electrically coupled to the anode 406 and the relay418. The relay 418 is electrically coupled to the two electrodes 408,410.

The relay 418 may be changeover switches having two switch positions.The relay 418 allows one electrical circuit between the electrode 408and the anode 406 to switch a second electrical circuit between theelectrode 410 and the anode 406, which can be separated from the first.

The electroplating solution 416 may comprise metal ion, conductivepolymer or a combination thereof. Various types of metals or conductivepolymer for the electroplating solution 416 may be used to formconductive bridges among the CNTs at intertube junctions. Theelectroplating solution 416 may have a composition suitable forelectroplating a particular conductive material.

The electroplating substance (indicated by the symbol “ES”) of theelectroplating solution 416 comprises metal, conductive polymer, or acombination thereof. This means that the metal ion and/or conductivepolymer of the electroplating solution 416 work as the electroplatingsubstance. When the electroplating substance, which forms conductivebridges among the different CNTs at intertube junctions, comprisesmetal, the metal as an electroplating substance is at least one selectedfrom the group consisting of Al, Cr, Co, Ni, Cu, Zn, Rh, Pd, Ag, Sn, W,Pt, Au, Ti, Mn, Cd and Pb. In some embodiments, the metal bridges aremade from the above-described process by using Cu, Au, Ni and the like.For example, Cu may be used as the electroplating substance, and asulfuric acid bath (0.75M of CuSO₄.5H₂O+74 g/L of H₂SO₄+0.2 g/L ofgelatin) may be prepared as the electroplating solution 416. In otherembodiments, Au may be used as the electroplating substance and anAu-bath (12 g/L of KAu(CN)₂+90 g/L of C₆H₅Na₃O₇.2H₂O) may be prepared asthe electroplating solution 416. According to alternative embodiments,Ni may be used as the electroplating substance, and a sulfamate-chloridebath (600 g/L of Ni(SO₃NH₂)₂.4H₂O+5 g/L of NiCl₂.6H₂O+45 g/L of H₃BO₃)may be prepared as the electroplating solution 416.

When the electroplating substance comprises a conductive polymer, theconductive polymer is at least one selected from the group consisting ofpolyaniline, polyimide, polyester, polyacetylene, polypyrrole,polythiophene, poly-p-phenylenevynilene, polyepoxide,polydimethylsiloxane, polyacrylate, poly methyl methacrylate, celluloseacetate, polystyrene, polyolefin, polymethacrylate, polycarbonatepolysulphone, polyethersulphone, and polyvinyl acetate.

The anode 406 is selected from the group consisting of Al, Cr, Co, Ni,Cu, Zn, Rh, Pd, Ag, Sn, W, Pt, Au, Ti, Mn, Cd and Pb. In theelectroplating process, the same type of metal used as theelectroplating substance may be used as the anode 406. If theelectroplating substance is conductive polymers, by way of non-limitingexample, Pt, Ag, Cu or Ni may be used as the anode 406.

Any metal having good conductivity may be used as a material for theelectrodes 408, 410. By way of non-limiting example, stainless, Cu, Nior Al may be used as the electrodes 408, 410.

The substrate 414 may be selected, but is not limited to, from the groupconsisting of glass, glass wafer, silicon wafer, quartz, plastic, andtransparent polymer.

In operation, the CNT network 412 attached to the two electrodes 408,410 is immersed into the electroplating solution 416 contained in thecontainer 404. In further embodiments, the CNT network 412 attached tothe two or more electrodes 408, 410 may be supported in theelectroplating solution 416 by a support mechanism (not shown in FIG.4).

An electrical potential generated by the power supply 402 is appliedacross the anode 406 and one of the two electrodes 408, 410 immersed inthe container 404, causing the CNT network 412 to be electroplated withthe electroplating substance. According to an alternative embodiment,the CNT network 412 itself may work as an electrode without the need forany other electrode. In this case, the power supply 402 can be directlycoupled to the two opposite ends of the CNT network 412.

The power supply settings can be voltage settings or current settings.Further, one or more rectifiers (not shown in FIG. 4) can be interposedbetween the power supply 402 and the relay 418 and/or between the powersupply 402 and the anode 406. The density, shape and size of conductivebridges that is electroplated on the CNT network 412 may be controlledby the voltage level, the current level, the content of theelectroplating substance or the combination thereof. In operation, theelectrical current density may range from about 1 nA/cm² to about 1000mA/cm².

When an electrical potential is applied to the CNT network 412, anelectrical potential drop can be generated at junctions among thedifferent CNTs, causing a temperature difference in the CNT network 412.That is, the temperature around the junctions between the different CNTscan be higher than that of other regions of the CNT network 412. Owingto the potential drop and/or the temperature difference, theelectroplating substance such as metal or conductive polymer isselectively attracted to the position of junctions among the differentCNTs and predominately electroplated thereon, bridging the differentCNTs to each other.

After a predetermined time period, the relay 418 is switched to supplyelectrical energy from one electrode, for example, electrode 408, to theother electrode, for example, electrode 410. The electroplating isfurther conducted under conditions effective to form uniform conductivebridges between different CNTs through one or more relays of theelectrical circuit. The length of the relay time period and thefrequency of the relay can be determined by routine experimentation. Asa result, contact resistances between different CNTs can besignificantly reduced. The transparency of the produced nano-compositecan be controlled within the range of being useful for its uses byadjusting electroplating conditions.

In certain embodiments, one or more detectors, for example detectors420, 422 in FIG. 4, may be coupled between the anode 406 and the twoelectrodes 408, 410 in order to measure electrical values such asvoltage and electric current. Resistance value and/or transparency valuecan be calculated from the measured electrical value and used foradjusting electroplating conditions. Further, resistance value and/ortransparency values can be used for checking whether the electroplatingis conducted to have targeted physical properties and/or for determiningthe completion time of the electroplating.

In certain embodiments, the electroplating apparatus 400 may comprise acontroller 424 such as, by way of example and not a limitation, acomputer. The controller 424 may operate under the control of a computerprogram stored on the hard disk drive or through other computerprograms, such as programs stored on a removable disk. In someembodiments, the controller 424 may be a programmable logic computer(PLC), such as an Allen-Bradley Controllogix Processor or a Modicon PLC.The controller 424 can receive input signals from various components ofthe apparatus 400 and control a particular parameter of the apparatus400 based on these signals. For example, the controller 424 iselectrically coupled to the power supply 402 and/or the relay 418 andoptionally the detectors 420, 422 for controlling the electroplatingconditions such as voltage, electric current, electroplating time,switching period. In this manner, relatively instantaneous adjustmentscan be made regarding the electroplating conditions within theelectroplating apparatus 400.

The electroplating apparatus 400 is able to prevent conductive bridgesfrom being dominantly formed at certain regions of the CNT network 412since the direction of electrical energy flow is alternately changedfrom one electric circuit to the other electric circuit through the twoelectrodes 408, 410. In this way, it is possible to produce anano-composite having uniform conductive bridges over the CNT network412 in a simple and efficient fashion without damaging physicalproperties such as resistance and transparency.

Depending on the design requirements and/or the application field, thenumber and arrangement of electrodes may have various types. Forexample, another illustrative embodiment of an electroplating apparatus500 for manufacturing a nano-composite may have four electrodes 508,510, 512, 514 attached to a CNT network 516 as illustrated in FIG. 5. Asdepicted, the electroplating apparatus 500 includes a power supply 502,a container 504, an anode 506, the four electrodes 508, 510, 512, 514,the CNT network 516, a substrate 518, an electroplating solution 520,and a relay 522. The power supply 502 is electrically coupled to theanode 506 and the relay 522. The relay 522 is electrically coupled tothe four electrodes 508, 510, 512, 514.

The relay 522 may be changeover switches having four switch positions.The relay 522 may allow one electrical circuit between one of the fourelectrodes 508, 510, 512, 514 and the anode 506 to alternatively switchanother electrical circuit between another of the four electrodes 508,510, 512, 514 and the anode 506, which can be separated from oneanother. Any one of many approaches for relaying an electrical energyflow among the plurality of electrodes 508, 510, 512, 514 can beemployed. The relay 522 may allow two electrical circuits to be on atthe same time and then to be switched to the other two electricalcircuits. For example, at the commencement of the electroplating, therelay 522 is set to electrically connect the anode 506 with the twoelectrodes 508, 512 at the same time for generating two electricalcircuits. After a predetermined period of time, the relay 522 isswitched to the positions to connect the anode 506 with the other twoelectrodes 510, 514.

The types of materials used for the electroplating substance (indicatedby the symbol “ES”), the anode 506, the electrodes 508, 510, 512, 514,and the substrate 518 of the electroplating apparatus 500 may be thesame with those described regarding FIG. 4. The electroplating apparatus500 may also further comprise a support mechanism and/or one or morerectifiers.

The power supply settings can be voltage settings or current settings.The voltage level, the current level or the concentration of theelectroplating substance is adjusted to control density and size of theelectroplating substance that is electroplated on the CNT network 516.

In certain embodiments, one or more detectors (524, 526, 528, and 530 inFIG. 5) may be coupled between the anode 506 and the four electrodes508, 510, 512, 514 in order to measure the electrical value such asvoltage and electric current. In further embodiments, the electroplatingapparatus 500 may comprise a controller 532. The controller 532 may beelectrically coupled to the power supply 502 and/or the relay 522 and,optionally, the detectors 524, 526, 528, 530 for controlling theelectroplating conditions such as voltage, electric current,electroplating time, switching period. In some embodiments, two of morepower supplies can be used instead of only one power supply 502.

The density, shape and size of conductive bridges that is electroplatedon the CNT network 516 is controlled by the voltage level, the currentlevel, the content of the electroplating substance or the combinationthereof.

According to alternative embodiments, the relay 522 may have many moresets of switch contacts, and the direction, order, and number ofrelaying the electrical energy flow can be varied as necessary.

In some embodiments, to further enhance the properties of thenano-composite according to its uses, various post-treatments may beemployed, including UV-irradiation, thermal annealing, electroplating,and the like.

FIG. 6 shows a schematic diagram of an illustrative embodiment of theCNT network 412 with metal (indicated by the symbol “M”) bridges. Thesize of the metal bridges ranges, but is not limited to, from about 0.5nm to about 10 nm.

FIG. 7 illustrates a schematic diagram of an illustrative embodiment ofthe CNT network 412 with conductive polymer (indicated by the symbol“CP”) bridges. As illustrated in FIG. 7, the conductive polymer easilypenetrates into the narrow space among CNTs at the junctions due tocapillary action. The conductive polymer inserts into or wraps aroundthe junctions among the different CNTs to produce the nano-compositehaving conductive bridges.

As depicted in FIGS. 6 and 7, the nano-composite include the CNT network412 having one or more intertube junctions among the two or more CNTsand electroplating substance associated with the CNT network 412, wherea predominant amount of the electroplating substance is present at theone or more intertube junctions, and where the electroplating substanceprovides one or more conductive bridges among the two or more CNTs.About 70 to about 100% of the electroplating substance associated withthe CNT network may be present at intertube junctions among differentCNTs.

According to the present disclosure, it is possible to evenly depositelectroplating substance at junctions between CNTs by changing theposition of the working electrodes through a relay and thus improveerosion of the electroplating coating to provide uniform distribution ofthe conductive bridges on the CNT network. Contact resistances amongdifferent CNTs can also be regular over the nano-composite. Thenano-composite of the present disclosure may have a sheet resistance offrom about 1 Ω/sq to about 1000 Ω/sq depending on its uses. Further, thetransparency of the produced nano-composite can be controlled to have anarrow standard deviation.

FIG. 8 is a flow chart of an illustrative embodiment for manufacturing aCNT network-based nano-composite. At block 820, a CNT network may beprepared by using various techniques such as dip-coating, spin coating,bar coating, spraying, self-assembly, Langmuir-Blodgett deposition,vacuum filtration, and the like.

In order to form a CNT network, the CNT colloidal solution may beprepared by dispersing purified CNTs in a solvent, such as deionizedwater or an organic solvent, for example, 1,2-dichlorobenzene, dimethylformamide, benzene, methanol, and the like. Since the CNTs produced bythe currently available methods may contain impurities, they may need tobe purified before being dispersed into the solution. The purificationmay be performed by wet oxidation in an acid solution or dry oxidation.A suitable purification method may comprise refluxing CNTs in a nitricacid solution (e.g., about 2.5 M), re-suspending the CNTs in water witha surfactant (e.g., sodium lauryl sulfate, sodium cholate) at pH 10, andthen filtering the CNTs using a cross-flow filtration system. Theresulting purified CNT suspension may then be passed through a filter,such as a polytetrafluoroethylene filter. Alternatively, purified CNTscan be purchased directly.

The purified CNTs may be in a powder form that can be dispersed into thesolvent. In certain embodiments, an ultrasonic wave or microwavetreatment can be carried out to facilitate the dispersion of thepurified CNTs throughout the solvent. The dispersing may be carried outin the presence of a surfactant. Various types of surfactants may beused including, but not limited to, sodium dodecyl sulfate, sodiumdodecylbenzenesulfonate, sodium dodecylsulfonate, sodiumn-lauroylsarcosinate, sodium alkyl allyl sulfosuccinate, polystyrenesulfonate, dodecyltrimethylammonium bromide, cetyltrimethylammoniumbromide, Brij, Tween, Triton X, and poly(vinylpyrrolidone). In this way,a well-dispersed and stable CNT colloidal solution is prepared.

A substrate can be prepared with surface treatment for high wettability.Considering that a post-wet-process is required after a CNT network isformed, a hydrophilic SAM (self assembled monolayer) coating or piranha(H₂SO₄:H₂O₂=4:1)-treatment may be adopted to increase the adhesion forcebetween CNTs and the substrate. CNTs can be coated on the substrate withthe prepared colloidal solution by various methods including dipcoating, spraying, spin coating and so on. Then a CNT network is formedon the substrate.

At block 840, the CNT network is immersed into an electroplatingsolution to perform electroplating. The CNT network can be attached totwo or more electrodes arranged at predetermined intervals or work as anelectrode itself to which a power supply is electronically coupledthrough two or more parts thereof at predetermined intervals. Theelectroplating solution comprises metal ions, conductive polymers, or acombination thereof.

At block 860, electrical energy is applied across an anode and a portionof two or more electrodes that are immersed in the electroplatingsolution, and then the electroplating substance of the electroplatingsolution is applied to the CNT network.

At block 880, the electrical energy flow is relayed from a portion oftwo or more electrodes to another portion of two or more electrodesunder conditions effective to produce a nano-composite having uniformconductive bridges of the electroplating substance at junctions betweenthe different CNTs.

In this way, electroplated metals or conductive polymers may work asbridges between different CNTs, thereby reducing the electricalresistance of the CNT network and increasing adhesion between the CNTnetwork and a substrate. Further, the transparency of the nano-compositecan be adjusted to the desired level based on the amount, density, shapeand size of conductive bridges, which can be controlled by varyingelectroplating conditions such as voltage level, current level, theconcentration of the electroplating substance, or the combinationthereof.

In accordance with the present disclosure, a TCE is provided comprisingthe nano-composite described above, which can replace brittle andexpensive ITO electrodes. Further, a nano-composite of the presentdisclosure can be applied to various fields such as flexible displays,Electromagnetic-interference (EMI) shielding material, and Organic LightEmitting Diodes (OLED).

The following examples are provided for illustration of some of theillustrative embodiments of the present disclosure but are by no meansintended to limit their scope.

Example 1 Preparation of a Nano-Composite Preparation of a CNT Network

Sonication is conducted for about 30 min in nitric acid to purify CNTs(product number: ASP-100F, Iljin Nanotech). The CNTs are neutralizedusing D.I. water after wet-oxidization and then passed through vacuumfiltration. The purified CNTs are dispersed in 1,2-dichlorobenzene. Anultrasonication treatment is carried out for about 10 hr to facilitatedispersion of the purified CNTs throughout the solvent. In this way, thewell-dispersed and stable CNT colloidal solution is prepared. A sodalime glass is used as a substrate. Piranha (H₂SO₄:H₂O₂=4:1)-treatment isadopted to remove impurities on the surface of the substrate and modifythe surface of the substrate so as to have polarity, thereby increasingthe adhesion force between CNTs and the substrate. The glass substrateis immersed vertically into the CNT colloidal solution and dip-coatingis performed with the withdrawal velocity of 3 mm/min at roomtemperature to produce a CNT network.

Preparation of a Nano-Composite Using Electroplating

A nano-composite having conductive bridges on the CNT network isprepared by the following process. Cu is used as an anode and a sulfuricacid bath (0.75M of CuSO₄.5H₂O+74 g/L of H₂SO₄+0.2 g/L of gelatin) isprepared as an electroplating solution. The CNT network attached to twoelectrodes at opposite ends thereof is immersed into the electroplatingsolution. Electrical energy is applied between the anode and one of theelectrodes and then the electrical energy flow is switched to thecircuit between the anode and the other electrode, producing anano-composite having uniform Cu bridges at junctions among thedifferent CNTs. Electroplating is performed with a current density of 10mA/cm² at room temperature. Electrical resistance is measured using a4-point probe (model: CMT-SR2000N, AIT) and transparency is observedusing an ultraviolet-visible spectrophotometer (model: Lambda-20, PerkinElmer). The nano-composite has 90 Ω/sq of resistance and about 85% oftransparency.

Those skilled in the art will appreciate that, for this and otherprocesses and methods disclosed herein, the functions performed in theprocesses and methods may be implemented in differing order.Furthermore, the outlined steps and operations are only provided asexamples, and some of the steps and operations may be optional, combinedinto fewer steps and operations, or expanded into additional steps andoperations without detracting from the essence of the disclosedembodiments.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, other differentcomponents. It is to be understood that such depicted architectures aremerely exemplary, and many other architectures can be implemented whichachieve the same functionality. In a conceptual sense, any arrangementof components to achieve the same functionality is effectively“associated” such that the desired functionality is achieved. Hence, anytwo components herein combined to achieve a particular functionality canbe seen as “associated with” each other such that the desiredfunctionality is achieved, irrespective of the architectures orintermediate components. Likewise, any two components so associated canalso be viewed as being “operably connected”, or “operably coupled”, toeach other to achieve the desired functionality, and any two componentscapable of being so associated can also be viewed as being “operablycoupled”, to each other to achieve the desired functionality. Specificexamples of being operably coupled include but are not limited tophysically matching and/or physically interacting components and/orwirelessly interacting and/or wirelessly interacting components and/orlogically interacting and/or logically interacting components.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, to gain a betterunderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense wherein one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, and C” would include but not be limited to systems thathave A alone, B alone, C alone, A and B together, A and C together, Band C together, and/or A, B, and C together, etc.). In those instanceswhere a convention analogous to “at least one of A, B, or C, etc.” isused, in general such a construction is intended in the sense whereinone having skill in the art would understand the convention (e.g., “asystem having at least one of A, B, or C” would include but not belimited to systems that have A alone, B alone, C alone, A and Btogether, A and C together, B and C together, and/or A, B, and Ctogether, etc.). It will be further understood by those within the artthat virtually any disjunctive word and/or phrase presenting two or morealternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” will be understood to include the possibilities of “A”or “B” or “A and B.”

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

1. An electroplating apparatus for manufacturing a nano-compositecomprising: a power supply configured to generate electrical energy; acarbon nanotube network; an electroplating solution comprising any oneselected from the group consisting of metal ion, conductive polymer, anda combination thereof; an anode coupled to the power supply and immersedin the electroplating solution; two or more electrodes attached to thecarbon nanotube network at predetermined intervals and immersed in theelectroplating solution; and a relay coupled to the power supply and thetwo or more electrodes and configured to switch over the electricalenergy flow from a portion of the two or more electrodes to anotherportion of the two or more electrodes.
 2. The apparatus of claim 1,wherein the anode is selected from the group consisting of Al, Cr, Co,Ni, Cu, Zn, Rh, Pd, Ag, Sn, W, Pt, Au, Ti, Mn, Cd and Pb.
 3. Theapparatus of claim 1 further comprising: one or more detectorspositioned to measure the electrical value between the anode and the twoor more electrodes.
 4. The apparatus of claim 1 further comprising: acontroller coupled to the power supply and/or the relay.
 5. Anelectroplating apparatus for manufacturing a nano-composite comprising:a power supply configured to generate electrical energy; anelectroplating solution comprising any one selected from the groupconsisting of metal ions, conductive polymers, and a combinationthereof; an anode coupled to the power supply and immersed in theelectroplating solution; a carbon nanotube network coupled to the powersupply through two or more parts thereof at predetermined intervals andimmersed in the electroplating solution; and a relay coupled to thepower supply and the two or more parts of the carbon nanotube networkand configured to switch over the electrical energy flow from a portionof the two or more parts of the carbon nanotube network to anotherportion of the two or more parts of the carbon nanotube network.
 6. Theapparatus of claim 5, wherein the anode is selected from the groupconsisting of Al, Cr, Co, Ni, Cu, Zn, Rh, Pd, Ag, Sn, W, Pt, Au, Ti, Mn,Cd and Pb.
 7. The apparatus of claim 5 further comprising: one or moredetectors positioned to measure the electrical value between the anodeand the carbon nanotube network.
 8. The apparatus of claim 5 furthercomprising: a controller coupled to the power supply and/or the relay.9. A method for manufacturing a nano-composite using electroplatingcomprising: forming a carbon nanotube (CNT) network having one or moreintertube junctions between different carbon nanotubes; immersing thecarbon nanotube network attached to two or more electrodes which arearranged at predetermined intervals into an electroplating solution;applying an electrical energy among an anode and a portion of the two ormore electrodes for applying an electroplating substance of theelectroplating solution to the carbon nanotube network; and relaying theelectrical energy flow from a portion of the two or more electrodes toanother portion of the two or more electrodes under conditions effectiveto produce a nano-composite having uniform conductive bridges of theelectroplating substance at the one or more intertube junctions.
 10. Themethod of claim 9, wherein the time period and frequency of relaying theelectrical energy flow is adjusted to reduce the contact resistance ofthe CNT network.
 11. The method of claim 9, wherein the anode isselected from the group consisting of Al, Cr, Co, Ni, Cu, Zn, Rh, Pd,Ag, Sn, W, Pt, Au, Ti, Mn, Cd and Pb.
 12. The method of claim 9, whereinthe applying of electrical energy and the relaying of the electricalenergy flow is performed with an electrical current density ranging fromabout 1 nA/cm² to about 1000 mA/cm².
 13. The method of claim 9, whereinthe electroplating substance comprises any one selected from the groupconsisting of metal, conductive polymer, and a combination thereof. 14.The method of claim 13, wherein the metal is at least one selected fromthe group consisting of Al, Cr, Co, Ni, Cu, Zn, Rh, Pd, Ag, Sn, W, Pt,Au, Ti, Mn, Cd and Pb.
 15. The method of claim 13, wherein theconductive polymer comprises at least one selected from the groupconsisting of polyaniline, polyimide, polyester, polyacetylene,polypyrrole, polythiophene, poly-p-phenylenevynilene, polyepoxide,polydimethylsiloxane, polyacrylate, poly methyl methacrylate, celluloseacetate, polystyrene, polyolefin, polymethacrylate, polycarbonatepolysulphone, polyethersulphone, and polyvinyl acetate.
 16. The methodof claim 9, wherein the size of the conductive bridges ranges from about0.5 nm to about 10 nm when the electroplating substance is metal. 17.The method of claim 9, wherein the forming of the carbon nanotubenetwork is carried out by any one selected from the group consisting ofdip-coating, spin coating, bar coating, spraying, self-assembly,Langmuir-Blodgett deposition, and vacuum filtration.
 18. The method ofclaim 9 further comprising: measuring the electrical value between theanode and the two or more electrodes.
 19. A method for manufacturing anano-composite using electroplating comprising: forming a carbonnanotube (CNT) network having one or more intertube junctions betweendifferent carbon nanotubes; immersing the carbon nanotube network intoan electroplating solution, wherein the carbon nanotube network iscoupled to a power supply through two or more parts thereof atpredetermined intervals; applying an electrical energy among an anodeand a portion of the two or more parts of the carbon nanotube networkfor applying an electroplating substance of the electroplating solutionto the carbon nanotube network; and relaying the electrical energy flowfrom a portion of the two or more parts of the carbon nanotube networkto another portion of the two or more parts of the carbon nanotubenetwork under conditions effective to produce a nano-composite havinguniform conductive bridges of the electroplating substance at the one ormore intertube junctions.
 20. The method of claim 19, wherein the timeperiod and frequency of relaying the electrical energy flow is adjustedto reduce the contact resistance of the CNT network.
 21. The method ofclaim 19, wherein the anode is selected from the group consisting of Al,Cr, Co, Ni, Cu, Zn, Rh, Pd, Ag, Sn, W, Pt, Au, Ti, Mn, Cd and Pb. 22.The method of claim 19, wherein the applying of electrical energy andthe relaying of the electrical energy flow is performed with anelectrical current density ranging from about 1 nA/cm² to about 1000mA/cm².
 23. The method of claim 19, wherein the electroplating substancecomprises any one selected from the group consisting of metal,conductive polymer, and a combination thereof.
 24. The method of claim23, wherein the metal is at least one selected from the group consistingof Al, Cr, Co, Ni, Cu, Zn, Rh, Pd, Ag, Sn, W, Pt, Au, Ti, Mn, Cd and Pb.25. The method of claim 23, wherein the conductive polymer comprises atleast one selected from the group consisting of polyaniline, polyimide,polyester, polyacetylene, polypyrrole, polythiophene,poly-p-phenylenevynilene, polyepoxide, polydimethylsiloxane,polyacrylate, poly methyl methacrylate, cellulose acetate, polystyrene,polyolefin, polymethacrylate, polycarbonate polysulphone,polyethersulphone, and polyvinyl acetate.
 26. The method of claim 19,wherein the size of the conductive bridges ranges from about 0.5 nm toabout 10 nm when the electroplating substance is metal.
 27. The methodof claim 19, wherein the forming of the carbon nanotube network iscarried out by any one selected from the group consisting ofdip-coating, spin coating, bar coating, spraying, self-assembly,Langmuir-Blodgett deposition, and vacuum filtration.
 28. The method ofclaim 19 further comprising: measuring the electrical value between theanode and the carbon nanotube network.